ATOMS: ALMA Three-millimeter Observations of massive Star-forming regions – XX. Probability distribution function of integrated intensity for dense molecular gas tracers

ABSTRACT We report the observations of J = 1–0 of HCN, HCO$^+$, H$^{13}$CO$^{+}$, and H$^{13}$CN, HC$_3$N (J = 11–10) emission towards 135 massive star-forming clumps, as part of the ALMA Three-millimeter Observations of Massive Star-forming regions Survey. We present the integrated intensity probability distribution function (I-PDF) for these molecular tracers, modelled as a combination of a lognormal distribution and a power-law tail. The molecular line luminosities for the power-law tail segment, $L_{\rm mol}(p)$, have been calculated. We have investigated the correlation between the bolometric luminosity, $L_{\rm bol}$, and the power-law part of the molecular line luminosity, $L_{\rm mol}(p)$. Our findings suggest that the scaling relationships between $L_{\rm bol}$ and $L_{\rm mol}(p)$ for HCN and HCO$^+$ are sublinear, indicating that these molecules might not be the most effective tracers for the dense gas. In contrast, H$^{13}$CN and HC$_3$N exhibit a nearly linear relationship between $L_{\rm bol}$ and $L_{\rm mol}(p)$, indicating that they can well trace gravitationally bound dense gas. The ratios of $L_{\rm bol}$-to-$L_{\rm mol}(p)$, serving as indicators of star formation efficiency (SFE) within massive star-forming clumps, exhibit a weak anticorrelation with the power-law index in the I-PDF. In addition, the SFE is also weakly anticorrelated with the exponent $\alpha$ of the corresponding equivalent density distribution. Our results implie that clumps with substantial gas accumulation may still display low star formation efficiencies.

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Journal
Monthly Notices of the Royal Astronomical Society
Published
2025-02-26
DOI
https://doi.org/10.1093/mnras/staf176
Primary Topic
Astrophysics and Star Formation Studies
Type
article
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article

ATOMS: ALMA Three-millimeter Observations of massive Star-forming regions – XX. Probability distribution function of integrated intensity for dense molecular gas tracers

Tie Liu, Patricio Sanhueza, Fengwei Xu, Ke Wang et al.
Monthly Notices of the Royal Astronomical Society
Astrophysics and Star Formation Studies
article

ATOMS: ALMA Three-millimeter Observations of massive Star-forming regions – XX. Probability distribution function of integrated intensity for dense molecular gas tracers

Tie Liu, Patricio Sanhueza, Fengwei Xu, Ke Wang, Prasanta Gorai, M. Juvela, Feng-Yao Zhu, Sihan Jiao, Jinbo Wu, Zhiyuan Ren, L. Bronfman, L. Viktor Tóth, P. García, Hongli Liu, Di Li, Chao Zhang, Swagat Ranjan Das, Chang Won Lee, Guido Garay
article en

Abstract

ABSTRACT We report the observations of J = 1–0 of HCN, HCO$^+$, H$^{13}$CO$^{+}$, and H$^{13}$CN, HC$_3$N (J = 11–10) emission towards 135 massive star-forming clumps, as part of the ALMA Three-millimeter Observations of Massive Star-forming regions Survey. We present the integrated intensity probability distribution function (I-PDF) for these molecular tracers, modelled as a combination of a lognormal distribution and a power-law tail. The molecular line luminosities for the power-law tail segment, $L_{\rm mol}(p)$, have been calculated. We have investigated the correlation between the bolometric luminosity, $L_{\rm bol}$, and the power-law part of the molecular line luminosity, $L_{\rm mol}(p)$. Our findings suggest that the scaling relationships between $L_{\rm bol}$ and $L_{\rm mol}(p)$ for HCN and HCO$^+$ are sublinear, indicating that these molecules might not be the most effective tracers for the dense gas. In contrast, H$^{13}$CN and HC$_3$N exhibit a nearly linear relationship between $L_{\rm bol}$ and $L_{\rm mol}(p)$, indicating that they can well trace gravitationally bound dense gas. The ratios of $L_{\rm bol}$-to-$L_{\rm mol}(p)$, serving as indicators of star formation efficiency (SFE) within massive star-forming clumps, exhibit a weak anticorrelation with the power-law index in the I-PDF. In addition, the SFE is also weakly anticorrelated with the exponent $\alpha$ of the corresponding equivalent density distribution. Our results implie that clumps with substantial gas accumulation may still display low star formation efficiencies.

Monthly Notices of the Royal Astronomical SocietyVol. 538(1)
Eötvös Loránd University (HU), University of Debrecen (HU), University of Helsinki (FI), Taiyuan Normal University (CN), University of Cologne (DE), University of Oslo (NO), Yunnan University (CN), Chinese Academy of Sciences (CN), National Institutes of Natural Sciences (JP), Peking University (CN), Shanghai Astronomical Observatory (CN), Helsinki Institute of Physics (FI), Korea Astronomy and Space Science Institute (KR), Universidad Católica del Norte (CL), Kavli Institute for Theoretical Sciences (CN), FZU ‒ Institute of Physics of the Academy of Sciences of the Czech Republic (CZ), Zhejiang Lab (CN), National Astronomical Observatory of Japan (JP), National Astronomical Observatories (CN), University of Chile (CL), Korea University of Science and Technology (KR), Tsinghua University (CN)
Neurosciences Research Foundation, Japan Society for the Promotion of Science London, National Natural Science Foundation of China, Academy of Finland, Chinese Academy of Sciences, Korea Astronomy and Space Science Institute, Ministry of Education, Science and Technology, Chinese University Basal Research Fund Program, Agencia Nacional de Investigación y Desarrollo, Japan Society for the Promotion of Science, Fondo Nacional de Desarrollo Científico, Tecnológico y de Innovación Tecnológica, National Key Research and Development Program of China
Openalex Percentile: Top 98%
Astrophysics and Star Formation Studies
DOIOpen Access PDFOpenAlex
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